1. Field of the Invention
This invention relates to a catalytic oxidation process of ammonia, and more particularly, relates to a catalytic oxidation process of ammonia by contacting the ammonia recovered from coke oven gas with a particular catalyst in a fluidized state in the presence of oxygen gas such as contained in air to decompose it to nitrogen gas and water.
2. Description of the Prior Art
The gas generated from coke oven gas contains 6 to 10 g/Nm.sup.3 of ammonia. Since the ammonia corrodes piping as well as generating NO.sub.x through the combustion of the coke oven gas, it is necessary to be removed. A conventional method of removing ammonia from coke oven gas (COG) is conducted by washing the COG with dilute sulfuric acid to recover the ammonia as ammonium sulfate. However, the demand of ammonium sulfate for fertilizer has decreased, and the market price greatly lowered. As a result, the profit is remarkably inferior, and the ammonia removing process by the production of ammonium sulfate is now almost worthless in the industrial viewpoint. At present, the ammonium sulfate production process is reduced, and changed to other processes such as the Phosam process to produce highly pure liquid ammonia, the Koppers process to separate ammonia followed by direct combustion or the Carl Still process to burn ammonia in the presence of a catalyst. In the Carl Still process (Aromatics, vol. 29, No. 6, pp 7-12, 1977), ammonia in COG is absorbed by water or aqueous ammonia, and the aqueous ammonia is distilled to evaporate ammonia vapor. The ammonia vapor is burned completely in in combustion furnace for decomposition of ammonia at about 1000.degree. C. together with COG and air in the presence of catalyst. The heat of the exhaust gas of the combustion furnace is recovered, and then discharged to the atmosphere. The conventional processes have the following problems. In the conventional combustion processes, it is necessary to use heat-resistant materials for the reactor. Moreover, in the case of the direct combustion process, it is difficult to inhibit the production of NO.sub.x. On the other hand, in the case of the catalytic combustion process, severe conditions are employed compared with usual catalytic reactions, and the catalyst employed is therefore a special heat-resistant catalyst. The concentration of generated NO.sub.x is high, about 50 ppm.